A turbocharger is frequently used to increase the power output of an internal combustion engine. The turbocharger includes a turbine which is connected by a shaft to a compressor that is located between an air filter and an intake manifold. The turbocharger is typically mounted to an exhaust manifold of the engine such that exhaust gases from the engine cylinders cause the turbine and thus the compressor to spin. The compressor then pressurizes the air going into the engine cylinders to provide an elevated boost pressure which causes an increase in the power generated by the engine. Further, as engine speed is increased, more exhaust gases are generated thereby increasing boost pressure.
It is desirable to control the amount of boost pressure that is generated in order to reduce the likelihood of the occurrence of undesirable engine conditions such as engine knock. A method that is used to control boost pressure includes the use of a wastegate device. The wastegate device includes a door or flap which is opened at the appropriate time to allow exhaust gases to bypass the turbine. This causes the rotational speed of the turbine and the compressor to decrease, resulting in a decrease in the boost pressure level.
A wastegate actuator is used to control the opening and closing of the wastegate device. In many vehicles, the wastegate actuator is controlled by a solenoid. Many engines today are becoming smaller in capacity, resulting in smaller capacity alternators and thus less electrical power which is available for energizing such solenoids. Further, the amount of space available in current vehicle engine compartments is limited. Therefore, there is a need for solenoids which are smaller in size and which require less power for operation.